During layup of prepreg plies over a tool, it is sometimes necessary to closely conform the ply to curves, contours and/or features of the tool in order to assure that the layup is substantially free of voids, wrinkling and/or buckling. Known techniques for conforming plies to curved tool surfaces involve darting, cutting and/or splitting the ply during the layup process, and/or extensive hand sweeping to conform the ply to contoured tool surfaces. These techniques may be time consuming and/or may provide undesirable mechanical strength of the cured part. Another solution to the problem involves using relatively narrow slit prepreg tape in order to more closely conform the composite material to contoured tool surfaces. However the use of slit tape may increase material costs and reduce production rate since laying down slit tape may be more time consuming.
Accordingly, there is a need for a method of laying up a composite ply over a contoured tool that allows the ply to be deformed as it is applied to the tool in order to more closely conform the ply to tool contours while the ply remains accurately positioned. There is also a need for a method of handling and transporting ply material which allows the material to remain stable during transport and layup.